Nostradamus didn't get rich, he hid his visions in weird poetry so he didn't burnt at the stake
Never met the guy, but Wikipedia does state:
Final years and death
Nostradamus' current tomb in the Collégiale Saint-Laurent, Salon, into which his scattered remains were transferred after 1789.
By 1566, Nostradamus's gout, which had plagued him painfully for many years and made movement very difficult, turned into oedema, or dropsy. In late June he summoned his lawyer to draw up an extensive will bequeathing his property plus 3,444 crowns (around $300,000 US today), minus a few debts, to his wife pending her remarriage, in trust for her sons pending their twenty-fifth birthdays and her daughters pending their marriages.
Maybe he had a day job that paid better then he got from his writings?